The pursuit of biocompatible, breathable and skin-conformable wearable sensors has predominantly focused on synthetic stretchable hydrophobic polymers. Microbial nanocellulose (MNC) is an exceptional ...skin-substitute natural polymer routinely used for wound dressing and offers unprecedented potential as substrate for wearable sensors. A versatile strategy for engineering wearable sensing platforms is reported, with sensing units made of screen-printed carbon electrodes (SPCEs) on MNC. As-prepared SPCEs were used to detect the toxic metals cadmium (Cd2+) and lead (Pb2+) with limits of detection of 1.01 and 0.43 μM, respectively, which are sufficient to detect these metal ions in human sweat and urine. SPCEs functionalized through anodic pre-treatments were used for detecting uric acid and 17β-estradiol in artificial sweat, with detection limits of 1.8 μM and 0.58 μM, respectively. The electrochemical treatment created oxygen groups on the carbon surfaces, thus improving wettability and hydrophilicity. MNC was herein exploited as an adhesive-free, yet highly skin-adherent platform for wearable sensing devices that also benefit from the semi-permeable, non-allergenic, and renewable features that make MNC unique within the pool of materials that have been used for such a purpose. Our findings have clear implications for the developments on greener and more biocompatible but still efficient substrates and may pave the route for combining immunosensing devices with drug delivery therapies.
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•Skin-adherent biosensors based on pure nanocellulose fibers substrate.•SPCE on MNC enables the detection of uric acid, 17β-estradiol, Pb2+ and Cd2+ in sweat.•MNC membranes allow optimal skin integration in wearable technologies.
To address the problems associated with the use of unsupported nanomaterials, in general, and molybdenum disulfide (MoS2), in particular, we report the preparation of self-supported hybrid aerogel ...membranes that combine the mechanical stability and excellent textural properties of bacterial nanocellulose (BC)-based organic macro/mesoporous scaffolds with the excellent adsorption-cum-photocatalytic properties and high contaminant removal performance of MoS2 nanostructures. A controlled hydrothermal growth and precise tuning of the synthetic parameters allowed us to obtain BC/MoS2-based porous, self-supported, and stable hybrid aerogels with a unique morphology resulting from a molecular precision in the coating of quantum-confined photocatalytic MoS2 nanostructures (2–4 nm crystallite size) on BC nanofibrils. These BC/MoS2 samples exhibit high surface area (97–137 m2·g–1) and pore volume (0.28–0.36 cm3·g–1) and controlled interlayer distances (0.62–1.05 nm) in the MoS2 nanostructures. Modification of BC with nanostructured MoS2 led to an enhanced pollutants removal efficiency of the hybrid aerogels both by adsorptive and photocatalytic mechanisms, as indicated by a detailed study using a specifically designed membrane photoreactor containing the developed photoactive/adsorptive BC/MoS2 hybrid membranes. Most importantly, the prepared BC/MoS2 aerogel membranes showed high performance in the photoassisted in-flow removal of both organic dye (methylene blue (MB)) molecules (96% removal within 120 min, K obs = 0.0267 min–1) and heavy metal ions (88% Cr(VI) removal within 120 min, K obs = 0.0012 min–1), separately and/or simultaneously, under UV–visible light illumination as well as excellent recyclability and photostability. Samples with interlayer expanded MoS2 nanostructures were particularly more efficient in the removal of smaller species (CrO4 2–) as compared to larger (MB) dye molecules. The prepared hybrid aerogel membranes show promising behavior for application in in-flow water purification, representing a significant advancement in the use of self-supported aerogel membranes for photocatalytic applications in liquid media.
Paracetamol is an active ingredient commonly found in pharmaceutical formulations in combination with one of the following compounds: codeine, orphenadrine, promethazine, scopolamine, and tramadol. ...In this work, we propose a unique analytical method for determination of these active ingredients in pharmaceutical samples. The method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation was achieved on a fused silica capillary (50 cm total length, 40 cm effective length, and 50 μm id) using an optimized background electrolyte composed of 20 mmol/L β‐alanine/4 mmol/L sodium chloride/4 μmol/L sodium hydroxide (pH 9.6). Each sample can be analyzed in a single run (≤2 min) and the limits of detection were 2.5, 0.62, 0.63, 2.5, 15, and 1.6 μmol/L for scopolamine, tramadol, orphenadrine, promethazine, codeine, and paracetamol, respectively. Recovery values for spiked samples were between 94 and 104%.
•The amine-free dual-activated resin cement demonstrated improved color stability over the traditional one.•The amine-free and the pre-heated composite presented the highest color stability when ...considering the CIEDE2000 parameter.•The pre-heated composite presented the highest color stability when considering the CIELAB parameter.
To determine the curing potential and color stability of resin-based luting materials for aesthetic restorations.
Four resin-based luting agents were tested: traditional dual-activated resin cement (RelyX ARC, ARC), amine-free dual-activated resin cement (RelyX Ultimate, ULT), light-activated resin cement (RelyX Veneer, VEN), and pre-heated restorative resin composite (Filtek Supreme, PHC). Degree of C=C conversion was determined by infrared spectroscopy (n=3) with direct light exposure or with interposition of 1.5-mm-thick ceramic (e.max Press HT) between the luting material and light. The curing potential considered the ratio between these two scenarios. Color difference (n=6) was determined by CIELAB (ΔEab) and CIEDE2000 (ΔE00) methods, by spectrophotometer measurements made 24h after photoactivation and 90 days after storage in water. Data was submitted to ANOVA and Tukey’s test (α=0.05).
The luting agents affected both conversion and color stability. With ceramic, ARC produced the highest conversion among the tested groups (75±1%) and the pre-heated composite (PHC) the lowest one (51±3%), but the curing potential was similar for all materials. ULT produced lower ΔEab than ARC. PHC presented the lowest color difference when considered both CIELAB and CIE2000 methods (ΔEab 2.1±0.4; ΔE00 1.6±0.2).
All luting strategies presented high curing potential. Amine-free dual-activated material was able to reduce color difference than that formulated with the amine component. Pre-heated composite produced the least color variation after storage.
After the use of evaluation paste, residue can remain on the bonding surface. However, how adhesion to lithium disilicate ceramic is affected is unclear.
The purpose of this in vitro study was to ...determine the effectiveness of lithium disilicate cleaning after contamination with an evaluation paste and before the application of a resin cement.
Rectangular lithium disilicate (IPS e.max CAD) specimens were obtained with a simulated milled surface, crystallized, etched with 5% hydrofluoric (HF) acid, and contaminated with an evaluation paste. The cleaning methods tested were air-water spray (SPRAY), 37% phosphoric acid (HPO), ultrasonic bath (ULT), cleaning paste (IVOC), and a conventional surface treatment (HF + silane–HF+SIL). The control (CTRL) group was not contaminated. After silane had been applied, resin cement cylinders were fabricated and light polymerized. Half of the cylinders (n=56) were tested for microshear bond strength at baseline (24 hours), and the other half after 210 days of water storage and 25 000 thermal cycles. Surface roughness, failure analysis, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were performed. Statistical analysis was performed with the Kruskal-Wallis and Mann-Whitney tests for surface roughness and the 2-way ANOVA and Bonferroni post hoc tests for bond strength (α=.05).
At baseline, only SPRAY did not restore the bond strength compared with CTRL. After aging, the bond strengths of SPRAY and IVOC were lower than of CTRL (P<.05); no significant difference was found between CTRL, HPO, ULT, and HF+SIL (P>.05). EDS demonstrated the presence of carbon in the SPRAY and ULT groups, probably remnants of the evaluation paste. SEM analysis identified such remnants in the SPRAY group only.
For optimal bond strength between lithium disilicate and resin cement after evaluation paste use, cleaning the ceramic surface with 37% phosphoric acid, ultrasonic bath, or with hydrofluoric acid worked best.
•The hypercaloric diet impacted the metabolism of Mangalarga Marchador horses.•Serum cholesterol levels increased in horses subjected to hypercaloric diet.•Hypercholesterolemia was positively ...correlated to insulin dysregulation.
This study aimed to characterize and correlate physiological and metabolic changes in horses fed a hypercaloric diet (HD). Nine mature horses with a mean initial body condition score of 2.9 ± 1 (scale, 1–9) were fed a high-calorie diet for 5 months. Fasting blood samples were collected before the study and biweekly for the duration of the project to determine the concentrations of cholesterol (CHOL), very low (VLDL), low (LDL) and high-density (HDL) lipoproteins, triglycerides, non-esterified fatty acids, and fructosamine. A low-dose oral glucose tolerance test (LGTT) was conducted before, 75 and 150 days after HD introduction. Mean arterial blood pressure was measured monthly. Following HD introduction, CHOL, LDL, HDL, and fructosamine blood concentrations increased (P < 0.001). These four variables were also positively and significantly correlated with the blood insulin response to LGTT. These findings confirm the occurrence of hypercholesterolemia concomitantly with insulin dysregulation development in horses exposed to HD.
The high recurrence rates of denture stomatitis may be associated with the resistance of biofilms to therapeutics. Therefore, methods that provide biomaterials with antifungal properties are an ...attractive solution to improving microbial control.
The purpose of this in vitro study was to modify conventional polymethyl methacrylate (PMMA) through the incorporation of metal methacrylate monomers and to evaluate the physicomechanical and optical properties and antifungal activity of the modified materials.
Experimental denture base acrylic resins were fabricated through the addition of zirconium methacrylate (ZM), tin methacrylate (TM), and di-n-butyldimethacrylate-tin (DNBMT) to the liquid of a commercially available denture base PMMA resin. Unmodified PMMA resin was used as the control. The degree of conversion of the materials was tested through Fourier transform infrared spectroscopy (n=3). A digital spectrophotometer was used to assess the color change of the modified materials (n=8). Differences in Knoop hardness and roughness between experimental groups were also evaluated (n=8). A biofilm accumulation test with Candida albicans (ATCC 62342) (n=4) was performed for 5 days in Sabouraud broth culture supplemented with 10% sucrose. Data were subjected to analysis of variance and the post hoc Tukey honestly significant difference test (α=.05).
The degree of conversion and color-change values of the experimental materials were statistically similar to those of the control (P=.593). The incorporation of DNBMT significantly increased the hardness of the modified material (P=.014). The ZM, TM, and DNBMT groups had higher antifungal activity against C. albicans (P=.001) and lower roughness than the control group (control 0.65 ±0.05 μm; ZM 0.34 ±0.09 μm, TM 0.34 ±0.11 μm, and DNBMT 0.41 ±0.08 μm).
The metal-containing methacrylate monomers provided antifungal action to the modified materials without affecting the physicomechanical or optical properties of the denture base resin. ZM, TM, and DNBMT are potential reactive agents for the fabrication of PMMA denture base resins with antifungal properties.
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•A modificated GCE with a functionalized MWCNTs, cobalt phthalocyanine (CoPc) and gold nanoparticles (AuNPTs) was developed.•The oxidation mechanism of diethylstilbestrol (DES) was ...investigated by cyclic voltammetry.•CoPc-MWCNTs/AuNPTs/GCE exhibited good analytical performance to quantify DES in water and meat.
An analytical methodology for determination of diethylstilbestrol (DES) based on electrochemical response of this compound on glassy carbon electrode modified with gold nanoparticules (AuNPTs), multiwall carbon nanotubes (MWCNTs) and cobalt phtolocyanine (CoPc) was proposed. The modified electrode catalysed the electrochemical oxidation of DES and also improved the sensitivity in comparison with unmodified electrode. The experimental conditions were optimized and also the kinetic electrochemical parameters were also evaluated. From square wave voltammograms, the calibration curve for DES determination were obtained and the calculated detection and quantification limits were equal to 1.99×10−7molL−1 and the 6.64×10−7molL−1, respectively. The proposed electroanalytical methodology was successfully applied for DES determination in water, and meat with satisfactory results, showing that fabricated sensor has potential do be applied in laboratory practices for DES determination in complex samples.
Paracetamol, caffeine and ibuprofen are found in over‐the‐counter pharmaceutical formulations. In this work, we propose two new methods for simultaneous determination of paracetamol, caffeine and ...ibuprofen in pharmaceutical formulations. One method is based on high‐performance liquid chromatography with diode‐array detection and the other on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation by high‐performance liquid chromatography with diode‐array detection was achieved on a C18 column (250×4.6 mm2, 5 μm) with a gradient mobile phase comprising 20–100% acetonitrile in 40 mmol L−1 phosphate buffer pH 7.0. The separation by capillary electrophoresis with capacitively coupled contactless conductivity detection was achieved on a fused‐silica capillary (40 cm length, 50 μm i.d.) using 10 mmol L−1 3,4‐dimethoxycinnamate and 10 mmol L−1 β‐alanine with pH adjustment to 10.4 with lithium hydroxide as background electrolyte. The determination of all three pharmaceuticals was carried out in 9.6 min by liquid chromatography and in 2.2 min by capillary electrophoresis. Detection limits for caffeine, paracetamol and ibuprofen were 4.4, 0.7, and 3.4 μmol L−1 by liquid chromatography and 39, 32, and 49 μmol L−1 by capillary electrophoresis, respectively. Recovery values for spiked samples were between 92–107% for both proposed methods.
Highly transparent biocomposite based on bacterial cellulose (BC) mat modified with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) block copolymer (EPE) were fabricated in situ during ...biosynthesis of bacterial cellulose in a static culture from Gluconacetobacter xylinum. The effect of the addition to the culture medium of water-soluble EPE block copolymer on structure, morphology, crystallinity, and final properties of the novel biocomposites was investigated at nano- and macroscale. High compatibility between components was confirmed by ATR-FTIR indicating hydrogen bond formation between the OH group of BC and the PEO block of EPE block copolymer. Structural properties of EPE/BC biocomposites showed a strong effect of EPE block copolymer on the morphology of the BC mats. Thus, the increase of the EPE block copolymer content lead to the generation of spherulites of PEO block, clearly visualized using AFM and MO technique, changing crystallinity of the final EPE/BC biocomposites investigated by XRD. Generally, EPE/BC biocomposites maintain thermal stability and mechanical properties of the BC mat being 1 wt % EPE/BC biocomposite material with the best properties. Biosynthesis of EPE/BC composites open new strategy to the utilization of water-soluble block copolymers in the preparation of BC mat based biocomposites with tunable properties.
